Methods and devices for controlling an internal combustion engine are known. Internal combustion engines, especially Diesel engines, are frequently equipped with exhaust gas aftertreatment systems, which may especially include a particulate filter. To regenerate the particulate filter, temperatures above the usual exhaust gas temperatures are required. Without additional measures, the particles oxidize at ca 550 to 600° C. The lower temperature threshold for the oxidation may be reduced to about 250 to 350° C. by combining the particulate filter with a oxidation catalyst, by catalytic coating of the filter and/or by the addition of an additive.
If the particulate filter reaches a certain load, and if regeneration of the filter is not ensured because of the engine operating state, it is provided that the exhaust gas temperature is raised to the point where the particles rapidly burn off. In that case, so much heat is liberated by the oxidation that the particulate filter and the exhaust gas heat up further. This further speeds up the oxidation, the filter heating becomes even greater, and this may lead to damage of the filter under certain circumstances.
A supercritical heating of the filter may also occur if the operating manner of the engine is changed during the regeneration. A sudden transition to an overrun operation or a transition to idling operation withdraw from the particulate filter the necessary cooling by the high volume exhaust gas flow, or rather, they increase the burn-off speed by the increased supply of oxygen in the exhaust gas flow.